IUD-heavier bleeding

Hi, this is the second time I've had a coil put in. (This is a 10year one) my period was late by 6days. And the bleeding is awful. First day was old blood and second day wow!! It's never been this heavy. It's so heavy that it actually went through and into my jeans (luckily I was at home) at work tomorrow so dreading it. I've had this second one in for around 6months now and usually I bleed for a few days an then it's gone and usually in time

But not this time. Any ideas why?

Thanks